1. Field of the Invention
The present invention is related to a reticle pod, and more particularly, to an EUV pod with fastening structure.
2. Description of the Prior Art
In the rapidly developing modern semiconductor technology, optical lithography tool plays an important role. The pattern definition relies fully on optical lithography technology. In the application of optical lithography tool related to semiconductors, pre-designed circuit paths are fabricated as light-transparent reticle in specific form. Basing on the principle of exposure, after light from the light source passes through the reticle and is projected on a silicon wafer, specific circuit pattern can be exposed on the silicon wafer. However, since any kind of dust (such as particles, powders, and organic matters) that adhere to the reticle can result in quality degradation of projected pattern, the reticle used to produce pattern on silicon wafers is required to be kept absolutely clean. Therefore, a cleanroom environment is usually provided in ordinary wafer fabrication processes to prevent from contamination caused by particles in the air.
In recent years, in order to further scale down the chip feature sizes, EUV (extreme ultraviolet light) at a wavelength of 157 nm is applied in lithography tool for the pattern on reticle to be imaged with higher resolution when being projected on the surface of a silicon wafer. However, when EUV is applied, the requirements for cleanliness of reticle pod are also, relatively speaking, higher. Particles smaller than 30 μm are previously acceptable, but as far as reticle pods for use with EUV lithography techniques are concerned, only particles with sizes between 30 and 50 nm are acceptable.
As a result, anti-contamination reticle pods are used in modern semiconductor process to store and carry reticles and to maintain the cleanliness of reticles; on the other hand, anti-contamination storage containers for semiconductor components are also used for storing and carrying semiconductor components and also for maintaining the cleanliness of semiconductor components. Reticle pods are used in the semiconductor process for storing reticles and for facilitating the carrying and transporting of reticles between platforms in order to isolate reticles from the air and thus prevent haze from forming on the surface of reticles due to contamination of reticles caused by particles and chemical gas. Thus, in advanced semiconductor plants, the cleanliness of reticle pods or storage devices for semiconductor components is usually required to comply with the SMIF (Standard Mechanical Interface) standard, in other words, to be maintained at Class 1 or below.
In order to reduce contamination generated during the process of storing, manufacturing, and transporting, a technology that uses a double-layer container for isolating the reticle has been proposed in the prior art, wherein an inner container is used for carrying the reticle and an outer container is used for fastening the inner container therein. As shown in FIG. 8, the lower cover c and the upper cover d of an inner container cover the reticle e and fasten the reticle e within the inner container, and then the lower cover a and the upper cover b of an outer container cover the inner container and fasten the inner container within the outer container. In the double-layer pod structure, supporters disposed in an outer container are usually used for fastening the inner container. However, in such double-layer pod structure, the user is unable to determine whether the inner container is stably snap-fastened by the supporters of the outer container and is unable to make sure the positioning status of the reticle in the inner container either. In consideration of the aforementioned, the present invention provides a reticle pod in which supporters of the outer container are used to press retainers of the inner container and thus indirectly fasten the reticle inside for ensuring safety and stability of the reticle in the reticle pod.